1. Field of the Invention
The present invention relates to a semiconductor device, and more particularly, to an internal voltage converter of a semiconductor device.
2. Discussion of the Related Art
Generally, an internal voltage converter (IVC) included in a semiconductor device receives a DC voltage from an external power source, converts the DC voltage into a DC voltage level greater or smaller than the DC voltage, maintains the converted DC voltage level constant throughout operation, and supplies the converted DC voltage to an internal core block. The external power source, generated from an external voltage generator, maintains the DC input voltage constant using a plurality of devices and consumes a predetermined amount of power during this operation.
The internal DC voltage converted by the internal voltage converter and supplied to the internal core block is used as a supply voltage for driving the internal core block during normal operation mode and the internal DC voltage must be maintained constant to properly operate the internal core block. The internal core block may be a cell array block, a X-decoder block, a Y-decoder block, or a peripheral test circuit block in a semiconductor device. Or, the internal core block may be a chip for communication applications, which can be included in an IC (integrated circuit) card or smart card.
In mobile or portable devices such as cellular phones, PDA's, smart cards, etc., the internal core block and internal voltage converter of a semiconductor device consume a large percentage of the total power. Therefore, a power efficient core block and internal voltage converter facilitate a longer time of operation of the device between each battery recharge or replacement.
Many mobile devices utilize a standby mode during an idling period. In standby mode, the IVC supplies a rough or an imprecise DC voltage to the core block to maintain a previous operating state without performing any function and waits until receiving a command to resume normal operation. Since a conventional IVC of a semiconductor device receives a DC input voltage from an external reference voltage generator to generate an internal voltage irrespective of the IVC normal or stand-by modes, there is wastage in power consumption during standby mode because the external voltage generator continues to maintain the DC output voltage constant.
A need therefore exists for an internal voltage converter and method which discriminates an IVC stand-by state from a normal operation state and selects a voltage reference with low power consumption among selective voltage references in the IVC stand-by state to generate an internal voltage.